注意使用了w：作为前缀，这表示标记变量对于当前窗口来说始终是本地变量。
Note the use of the w: prefix, which means that the flag variable is always local to the current window.
如果我们开发的是几个标记或者定义有标记变量的标记，那么我们就会有多个标记处理程序类。
If we were developing several tags or defining tags with tag variables, we would have multiple tag handler classes.
应用推荐